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الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2605.23049

We present the demography of dust attenuation, including its mass dependence and redshift evolution, using spectroscopic samples of 34,182 SDSS galaxies at $$z\sim0.1$$ and 863 JWST/JADES galaxies at $$z\sim1.5$$--$$7$$. We find that, on average, $${\rm H\alpha}/{\rm H\beta}$$ ratios are comparable to the Case B recombination value at $$M_\ast \lesssim 10^9 M_\odot$$, and increase beyond $$M_\ast \sim 10^9 M_\odot$$ both at $$z\sim0.1$$ and $$1.5$$--$$7$$. We derive the nebular attenuation $$A_{\rm V, nebular}$$ from Balmer decrements and the stellar attenuation $$A_{\rm V, stellar}$$ from rest-frame UV--optical spectra with supplementary \textit{GALEX} data, via comparisons with stellar-population models and multiple attenuation curves in a consistent manner across cosmic time. We find no significant redshift evolution of $$A_{\rm V, nebular}$$ and $$A_{\rm V, stellar}$$ at fixed $$M_\ast$$ over $$z\sim0$$--$$7$$, forming a universal extinction relation, and both rise from $$0.2$$--$$0.4$$ at $$M_\ast \lesssim 10^9 M_\odot$$ to $$\sim1$$ at $$M_\ast \sim 10^{11} M_\odot$$. Interestingly, at $$M_\ast \gtrsim 10^9 M_\odot$$, $$A_{\rm V, nebular}$$ rises more steeply than $$A_{\rm V, stellar}$$. This correlation holds within an uncertainty of $$\sim\pm0.2$$ for various combinations of attenuation curves (Calzetti, SMC, and Milky Way). These results indicate that $$M_\ast \sim 10^9 M_\odot$$ is a transition mass in dust attenuation, whose low-mass behavior reflects dust widely distributed by feedbacks. These mass-dependent extinction results address the long-standing issue of appropriate choice of the stellar-to-nebular color excess ratio, $$f\equiv E(B-V)_{\rm stellar}/E(B-V)_{\rm nebular}=1.0$$ or $$0.44$$, and suggest that galaxy $$M_\ast$$ determines $$f$$ from $$\sim1.0$$ to $$\sim0.44$$ across low- to high-mass galaxies.